Improved lignocellulose saccharification of a Miscanthus reddish stem mutant induced by heavy‐ion irradiation

Abstract

Abstract Miscanthus is a promising lignocellulosic bioenergy crop for the production of cellulosic ethanol. The recalcitrance of lignocellulose hampers the efficient conversion of Miscanthus biomass to fermentable sugars. Therefore, screening of Miscanthus germplasms with enhanced lignocellulose saccharification efficiency is of important significance to the cellulosic ethanol production from Miscanthus biomass. In this study, we utilize heavy‐ion irradiation mutagenesis to establish a mutant library of Miscanthus lutarioriparius, and screened a reddish stem (rs) mutant with improved lignocellulose saccharification efficiency. The rs mutant was characterized by a noticeable reddish coloration in various lignified cell walls in phloem and vascular bundle sheath, whereas the biomass yield was not compromised. The reddish coloration was attributed to the reduced incorporation of several phenolic compounds including 3‐caffeoylquinic acid, dihydroflavonol and proanthocyanin A, which shared common precursors with lignin monolignol biosynthesis via the phenylpropanoid pathway. Correspondingly, the lignin content was decreased by 10.2% and the cellulose content was concomitantly increased by 9.5% in rs mutant compared with the control plant. Meanwhile, the saccharification efficiency was substantially improved by 22.4%–25.6% in rs mutant compared to the control, when the lignocellulosic biomass was pretreated with or without 1.5% H2SO4. The rs mutant identified here holds a potential utilization as an ideal candidate feedstock in cellulosic bioethanol production.

Keywords

• bioenergy crop
• heavy‐ion irradiation
• lignin
• lignocellulose
• Miscanthus
• recalcitrance